1. Field of the Invention
The invention relates to an optical module, and more particularly to an optical module with a positioning frame.
2. Description of the Prior Art
A liquid crystal display (LCD) is composed of two major parts, a backlight module and an LCD panel. The backlight module is utilized for providing uniform and steady illumination. The LCD panel is assembled on the illumination surface of the backlight module. By controlling the tilting angle of the LC (liquid crystal) molecules within the LCD panel, the optical transmission of the pixels within the LCD panel is adjusted to show the image.
As mentioned above, the illumination of the LCD is provided by the backlight module. Therefore, brightness, uniformity, contrast, and viewing angle of a LCD are deeply influenced by the characteristics of the backlight module.
In addition, various optical films, such as diffuser or prism sheet, are usually provided on the backlight to enhance the illumination distribution of the backlight module and also improve the image quality of the LCD.
FIG. 1 illustrates a schematic view of an optical film mounting on a frame of a conventional backlight module. There are two protrusions 101 on one side of an optical film 10, and each of the protrusions 101 includes a positioning hole. There are two positioning pillars 111 disposed on a frame 11. By penetrating the positioning pillars 111 through the positioning holes, and then fastened by a clip, the optical film 10 is thus fixed on the frame 11.
However, since another side of the optical film 10 is not properly fixed, the optical film can be easily shifted due to external forces and thus damages the optical film 10.
With reference to FIG. 2, which illustrates a schematic view of an optical film mounting on a frame of a backlight module of another prior art.
As shown in FIG. 2, two sides of the optical film 10 have two protrusions 101 respectively. The frame 11 has two positioning slots 112 on one side thereof. After inserting the protrusions 101 into the positioning slots 112, the other side of protrusions 101 is then fixed on the frame 11 through clips or adhesive.
However, in such construction, only the protrusions 101 on one side of the optical film 10 are lodged in the positioning holes 112, sliding caused by horizontal movement occurs easily. Moreover, the protrusions 101 snap easily while inserting into the positioning slots 112, and thus damage or even deform the optical film.
With reference to FIG. 3, which illustrates a schematic view of an optical film mounting on a frame of a backlight module of another prior art.
As shown in FIG. 3, the frame 11 has two hook protrusions 113. Two sides of the optical film 10 have two protrusions 101 respectively, and the protrusions 101 on one side of the optical film 10 have two fixing holes corresponding to the hook protrusions 113.
After inserting the hook protrusions 13 through the positioning holes of the protrusions 101, clips or adhesive are then applied to fix the other side of protrusions 101 on the frame 11 corresponding to a side with the hook protrusions 13. By means of the extending outwardly hooks of the hook protrusions 113, the optical film 10 is not taken off.
However, there still exists several disadvantages within the related art:
1. The hook protrusion can't prevent the optical film from slipping in the direction perpendicular to the light emitted surface.
2. The existence of the hook protrusions will apparently increase the thickness of the backlight module, and this violates the tendency of slim volume.